Magnetic ranging provides relative direction and distance of one well with respect to another. Several technologies for ranging are based upon launching a current at a known frequency from the earth's surface down the casing of a target well and receiving a signal radiated from that casing in a ranging well. Other types of excitation, such as injecting a current at a depth below the surface, are also used in the ranging technologies.
Such ranging operations may use a wireline tool to provide both relative direction and distance from the ranging well to the target well. During a drilling operation, the drill string is removed from the ranging well and the wireline tool is inserted in order to continually update the relative distance and direction of the ranging well to the target well. This may result in increased drilling time and greater cost due to the expense of repeatedly removing the drill string to insert the wireline tool.